There has been known an image reading device which includes an automatic document feeder (ADF) and can convey a sheet along a conveyance path from an upper path to a lower path through a curved path.
In an image reading device, a lower path extends obliquely in an upper direction toward a downstream side in a sheet conveyance direction. On an upper side of the lower path, a separation piece and a separation roller are disposed to be in contact with each other with an upper path interposed therebetween. In the separation piece, a portion formed in a flat plate shape is inclined obliquely along the upper path, thereby extending obliquely in the upper direction toward the downstream side in the sheet conveyance direction.
That is, in this image reading device, the lower path is inclined in the upper direction toward the downstream side, and the separation piece is inclined in the upper direction toward the downstream side. That is, the lower path and the separation piece are inclined in opposite directions with respect to a horizontal plane. Further, since the separation piece is disposed on an upper side of the lower path, the downstream end side of the separation piece is farther away from the lower path than the upstream end side, and the separation roller is disposed on the upper side of the separation piece. Therefore, in this configuration, a vertical dimension of an area where the lower path, the separation piece, and the separation roller are disposed increases, which would prevent a thickness-reduction of the device.
Incidentally, if it is desired to improve a separating performance of the separation roller, it is effective to increase a diameter of the separation roller. However, in view of the above circumstances, the vicinity of the separation roller is likely to have a large dimension in a vertical direction, which would prevent an increase of the diameter of the separation roller.